Aside from a handful of novels, they're mostly nonfiction books covering his and his foundation's broad range of interests. A lot of them are about transforming systems: how nations can intelligently develop, how to lead an organization, and how social change can fruitfully happen.

We went through the past four years of his book criticism to find the ones that he gave glowing reviews and that changed his perspective.

So it's no surprise that Gates enjoyed "Tap Dancing To Work," a collection of articles and essays about and by Buffett, compiled by Fortune magazine journalist Carol Loomis.

Gates says that anyone who reads the book cover-to-cover will walk away with two main impressions:

First, how Warren's been incredibly consistent in applying his vision and investment principles over the duration of his career;

... [S]econdly, that his analysis and understanding of business and markets remains unparalleled. I wrote in 1996 that I'd never met anyone who thought about business in such a clear way. That is certainly still the case.

Getting into the mind of Buffett is "an extremely worthwhile use of time," Gates concludes.

'Making the Modern World: Materials and Dematerialization' by Vaclav Smil

Amazon

Gates says his favorite author is Vaclav Smil, an environmental sciences professor who writes big histories of things like energy and innovation.

His latest is "Making the Modern World." It got Gates thinking.

"It might seem mundane, but the issue of materials — how much we use and how much we need — is key to helping the world's poorest people improve their lives," he writes. "Think of the amazing increase in quality of life that we saw in the United States and other rich countries in the past 100 years. We want most of that miracle to take place for all of humanity over the next 50 years."

To know where we're going, Gates says, we need to know where we've been — and Smil is one of his favorite sources for learning that.

'The Sixth Extinction: An Unnatural History' by Elizabeth Kolbert

amazon

It can be easy to forget that our present day is a part of world history. Gates says that New Yorker writer Elizabeth Kolbert's new book "The Sixth Extinction" helps correct that.

"Humans are putting down massive amounts of pavement, moving species around the planet, over-fishing and acidifying the oceans, changing the chemical composition of rivers, and more," Gates writes, echoing a concern that he voices in many of his reviews.

"Natural scientists posit that there have been five extinction events in the Earth's history (think of the asteroid that wiped out the dinosaurs)," he continues, "and Kolbert makes a compelling case that human activity is leading to the sixth."

To get a hint of Kolbert's reporting, check out the series of stories that preceded the book's publication.

'Stress Test: Reflections on Financial Crises' by Tim Geithner

Amazon

Gates stood at the center of an enormously complex system as the CEO of Microsoft. Timothy Geithner did much the same as US Treasury Secretary — and saw the structure fall down around him during the financial crisis.

"Geithner paints a compelling human portrait of what it was like to be fighting a global financial meltdown while at the same time fighting critics inside and outside the Administration as well as his own severe guilt over his near-total absence from his family," Gates says. "The politics of fighting financial crises will always be ugly. But it helps if the public knows a little more about the subject."

"Pinker presents a tremendous amount of evidence that humans have gradually become much less violent and much more humane," he says, in a trend that started thousands of years ago and continued until this day.

This isn't just ivory-tower theory. Gates says the book has affected his humanitarian work.

"As I'm someone who's fairly optimistic in general," he says, "the book struck a chord with me and got me to thinking about some of our foundation's strategies."

'The Man Who Fed the World' by Leon Hesser

Park East Press

Even though Gates can get a meeting with almost anyone, he can't land a sit-down with Norman Borlaug, the late biologist and humanitarian who led the "Green Revolution" — a series of innovations that kept a huge chunk of humanity from starving.

"Although a lot of people have never heard of Borlaug, he probably saved more lives than anyone else in history," Gates says. "It's estimated that his new seed varieties saved a billion people from starvation," many of whom were in India and Pakistan.

Borlaug was awarded the Nobel Peace Prize, the Presidential Medal of Freedom, and the Congressional Gold Medal for his efforts — and is one of only seven people to do so.

For Gates, Borlaug is a model in getting important work done in the world.

"Borlaug was one-of-a-kind," he says, "equally skilled in the laboratory, mentoring young scientists, and cajoling reluctant bureaucrats and government officials."

Hesser's "The Man Who Fed the World" lets you peer into the personality that saved a billion lives.

Gates says that the book serves as a reminder that the principles for building a winning business stay constant. He writes:

For one thing, there's an essential human factor in every business endeavor. It doesn't matter if you have a perfect product, production plan and marketing pitch; you'll still need the right people to lead and implement those plans.

Learning of the affections that Gates and Buffett have for this title, the business press has fallen similarly in love with the book. We put together a list of takeaways, while Slate quipped that "Business Adventures" is "catnip for billionaires."

'The Bully Pulpit: Theodore Roosevelt, William Howard Taft, and the Golden Age of Journalism' by Doris Kearns Goodwin

Amazon

Like us, Gates is fascinated by the way Theodore Roosevelt was able to affect his society — busting trusts, setting up a park system, and the like.

For this reason, Gates appreciates how Goodwin's biography uses the presidency as a lens for understanding the shift of society.

"How does social change happen?" Gates asks in his review. "Can it be driven by a single inspirational leader, or do other factors have to lay the groundwork first?"

He says that TR shows how many stakeholders need to be involved.

"Although he tried to push through a number of political reforms earlier in his career," Gates says, "[Roosevelt] wasn't really successful until journalists at 'McClure's' and other publications had rallied public support for change."

'The Rosie Project: A Novel' by Graeme Simsion

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Gates doesn't review a lot of fiction, but "The Rosie Project," which came on the recommendation of his wife Melinda, is an oddly perfect fit.

"Anyone who occasionally gets overly logical will identify with the hero, a genetics professor with Asperger's Syndrome who goes looking for a wife," he writes. "(Melinda thought I would appreciate the parts where he's a little too obsessed with optimizing his schedule. She was right.)"

The book is funny, clever, and moving, Gates says, to the point that he read it in one sitting.